This 90-year-old man presented with hematuria and was noted on cystoscopic exam to have a 10 cm. diameter broad-based, smooth, lobular bladder mass. The tumor was located along the left bladder wall with obstruction of left ureter. Imaging studies showed probable left iliac node involvement. Multiple fragments of friable tissue, measuring 1.5 x 1.5 x 0.4 cm in aggregate, were removed for histopathological evaluation. The patient eventually underwent radical cystectomy.
The tumor was large (10 cm.), smooth, broad-based, and lobulated (Fig. 5.1). Approximately two-thirds of the tumor was composed of typical infiltrating, high-grade papillary urothelial carcinoma (Fig. 5.2). However, the lamina propria contained scattered foci of delicate lace-like osteoid lined by oval to polygonal cells with scant cytoplasm, large hyperchromatic nuclei, and prominent nucleoli (Fig. 5.3A & Fig. 5.3B). The osteoid matrix was nicely highlighted by trichrome stain (Fig. 5.4). Focal cartilagenous differentiation was also present (Fig. 5.5). Areas of geographic necrosis (Fig. 5.6) and composed of high-grade malignant cells with a predominant spindle growth pattern were seen in rare fragments.
The differential diagnosis includes sarcomatoid urothelial carcinoma (Fig. 5.7), carcinosarcoma (Fig. 5.8), urothelial carcinoma with pseudosarcomatous stroma (Fig. 5.9), and primary osteosarcoma of bladder (Fig. 5.10).
Carcinosarcoma of Bladder (Composed of high-grade papillary urothelial carcinoma and chondroblastic osteosarcoma)
Key Features
Sarcomatoid urothelial carcinoma and carcinosarcoma are related but distinctive histological subtypes of bladder cancer (1-5). There is considerable confusion and disagreement in the literature regarding nomenclature and histogenesis of these tumors (10). Carcinosarcoma, sarcomatoid urothelial carcinoma, and malignant mixed mesodermal tumor have been used interchangably to refer to these tumors. We define sarcomatoid urothelial carcinoma as carcinoma with a sarcomatoid phenotype and reserve the term carcinosarcoma for tumors with distinct mesenchymal heterologus elements such as bone (as seen in this case), cartilage, and muscle etc. However, the attempt to distinguish between the two entities is an academic exercise and of no apparent clinical significance since their presentation, treatment, and prognosis are similar.
Both are extremely uncommon and show male predominance. They are usually seen in 7th and 8th decades of life with hematuria as the most common presenting symptom. Carcinosarcoma of bladder shows an association with previous cyclophosphamide chemotherapy or radiation therapy (6). This is significant because of a similar association between radiation therapy and carcinosarcoma of uterus. Recurrent urothelial carcinoma is the most common antecedent in cases of sarcomatoid urothelial carcinoma.
Grossly, both carcinosarcoma and sarcomatoid urothelial carcinoma result in bulky polypoid or nodular tumors (Fig. 5.1). The malignant epithelial component in sarcomatoid urothelial carcinoma usually is high grade papillary urothelial carcinoma. Occasionally, it may be low grade urothelial carcinoma, adenocarcinoma, squamous cell carcinoma, small cell carcinoma, or consist of mixed patterns. Some cases contain a pure spindle cell component only. The commonly seen sarcomatous components in carcinosarcoma include chondrosarcoma, leiomyosarcoma, malignant fibrous histiocytoma, osteosarcoma, fibrosarcoma, and rhabdomyosarcoma. The malignant epithelial and stromal components may be sharply demarcated from each other or may gradually merge with each other.
The diagnosis of carcinosarcoma and sarcomatoid urothelial carcinoma of bladder can be made on routine hematoxylin and eosin stains alone in most cases. Primay bladder sarcomas are extremely rare and every effort must be made to search for an epithelial component in a tumor seemingly composed of only mesenchymal elements. The differential diagnosis of carcinosarcoma includes urothelial carcinoma with osseous or cartilagenous metaplasia (7), and primary osteosarcoma or chondrosarcoma of bladder (8). Sarcomatoid urothelial carcinoma may be confused with pure sarcoma, and pseudosarcomatous myofibroblastic proliferations such as post-operative spindle cell nodule and inflammatory pseudotumor. (9).
Treatment of sarcomatoid urothelial carcinoma and carcinosarcoma is stage dependant. Since most patients usually present with a high stage malignancy, the preferred modalities of treatment include cystectomy or transurethral resection with or without radiation therapy and chemotherapy. Prognosis of both tumors is dismal with most patients dying within a few months of diagnosis. In a large series recently published by us, 79% of carcinosarcoma patients died at a mean of 17.2 months (range 1 to 48 months) where as 81% of patients with sarcomatoid urothelial carcinoma died at a mean of 9.8 months (range 1 to 73 months) (1). Pathological stage was the main predictor of patient survival, with no significant differences noted due to treatment, histological subtypes (carcinosarcoma vs. sarcomatoid urothelial carcinoma) and gender.
Follow-up: The surgery was uneventful; however, the post-operative recovery period was complicated by thrombo-embolic phenomena resulting in stroke. The patient expired 4 months after surgery.
